Finance calculator

Loan Amortization Calculator

Build an amortizing loan schedule: monthly payment, total interest, and the first twelve periods of principal, interest, and remaining balance.

Instant result

Result

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Enter values to calculate.

Inputs—

Mode—

Formula—

Formulas

Core equations used by this calculator.

PrimarySame PMT as loan payment; each period: interest = bal·r, principal = PMT − interest

iRuns locally in your browser. Results are informational — verify critical financial decisions independently.

How to use

Follow these steps for a clear answer.

1

Enter the known values

Fill in each field with amounts and rates as labeled.

2

Calculate

Results update as you type; compare scenarios below when available.

3

Read the outputs

Check the result panel for the primary figure and supporting totals.

Example calculations

Common configurations with formula and result.

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Worked example

250,000 · 6.5% · 30 yr → payment ≈ 1,580.17; first month interest ≈ 1,354.17

Same PMT as loan payment; each period: interest = bal·r, principal = PMT − interest

See result panel

Loan Amortization calculator specification

Version 1.0.0 · Last reviewed 2026-07-28

Definition: Amortization splits each payment into interest on the remaining balance and principal reduction. Early payments are interest-heavy; later payments are principal-heavy.
What it calculates: Payment, total interest, and a 12-period amortization summary.
Inputs: Values shown on the calculator form
Outputs: Primary result in the result panel
Formula: Same PMT as loan payment; each period: interest = bal·r, principal = PMT − interest
About this calculator

Amortization splits each payment into interest on the remaining balance and principal reduction. Early payments are interest-heavy; later payments are principal-heavy.

Formula

Same PMT as loan payment; each period: interest = bal·r, principal = PMT − interest

Example

250,000 · 6.5% · 30 yr → payment ≈ 1,580.17; first month interest ≈ 1,354.17
Assumptions: Fixed rates and terms as entered; no fees or taxes unless modeled.
Calculation runs locally in the browser.
Units: Currency units as entered (dimensionless rates in %)
Boundary conditions: Zero or missing required fields yield zero or empty results.
Negative inputs are treated as zero.
Example: 250,000 · 6.5% · 30 yr → payment ≈ 1,580.17; first month interest ≈ 1,354.17
Validation cases: 250000 · 6.5% · 30 yr → payment ≈ 1580.17
period 1 interest → ≈ 1354.17
0% rate → equal principal each month
Sources: Standard time-value-of-money / managerial accounting identities
Last reviewed: 2026-07-28
Calculation version: 1.0.0

Frequently asked questions

Key distinctions behind the calculation.

How does the Loan Amortization Calculator work?

It uses Same PMT as loan payment; each period: interest = bal·r, principal = PMT − interest. All math runs locally in your browser.

Can I share my inputs?

Yes. Use Copy link in the result panel — the URL stores your current inputs.